Grinding roll for flour mills



L.. SCHMIDT GRINDING ROLL FOR FLOUR MILLS Filed May '7, 1924 lid - spiral formation. This statement,

LUDTGl SCJUDT, OF ST. LOUIS, llfllfISSOURI, ASSIGNOR TO ESSMUELL MEL TUB,-

SHTNG- GOA OF ST. LOUIS, MISSOURI, A CORPORATION OF MISBOUI.

GRINDING ROLL FOR, FLOUR MILLS.

Application filed May 7,

To all wlwm it may concern:

Be it known that I, LUDWIG SCHMIDT, a citizen of the United States, residing in the city of St. Louis and State of Missouri, have invented new and useful Improvements in Grinding Rolls for Flour Mills, of which the following is a specification.

This invention relates to grinding rolls for use in' grinding cereals and particularly in reducing wheat to flour, and in such use, is especially applicable to the gradual reduction of middlings.

The invention has for its general object to provide an improved grinding or reducing surface on such a roll.

ln efiect, my invention .is an improvement over the character of grinding roll described and claimed in my pending application Ser. No. 645,169, filed June 12, 1923, and is characterized by the fact that the lines are substantially straight in place of curvilinear and have a direction of extension longitudinal of the roll and diagonal to the axial line thereof, the general effect being that of a surface provided with lines of scratches presenting a substantially however, is subject to the modification that the lines are not continuous in extent from one end of the cylinder or roll to the other, but are multiform as regards the longitudinal extension of the roll as well as with regard to the circumferential extension of the roll.

In the reduction of wheat to flour, corru gated rolls are employed in reducing the grain down to a certain stage in whichmiddlings are roduced, the corrugated rolls being usual y referred to as the break rolls. The middlings are composed of the hard granular portion of the grain, and the finer grades of flour are made from them. Tn their reduction, smooth rolls and finely corrugated rolls are employed.

The ordinary arrangement of grinding or reducing rolls involves two rolls set in close proximity to each other, one of the rolls being run at a slightly increased speed relative to the other.

Ori 'nally, in the reduction of middlings, smootl i and highly polished rolls were employed. It was soon found, however, that notwithstandin the difi'erential rate 'of speed at which t e rolls were run, the broken articles of grain did not pass readily tween the rolls, as the latter were too 1924. Serial No. 711,697.

for the smooth rolls, at least at the head of the middlings reduction system. Not only are the finest practicable corrugations in such a roll too coarse to reduce the middlings inthe manner desired, but it has been found to be almost impossible to secure accurateor uniform corrugation of the roll, due to mechan ical reasons not necessary to set forth here.

To obviate the use of finely corrugated rolls, a method was devised for producing rolls with a dull finish instead of the highly polished surface which had previously char acterized the smooth roll. The dull finish roll has been very extensively used, and, while it is an improvement over the polished roll, or the corrugated roll, it still presents the objection of being too smooth to cause the proper engagement and feed of the grain particles between the rolls. This is, to some extent, due to the fact that in producing the dull finish, such slight roughening of the surface as is caused by the emery Wheel is along lines extending circumferentially of the roll, and hence only a slight increase in the gripping action of the roll is afforded.

According to the present invention, T pro vide for imparting a uniform degree of scratching on the surface of the roll, the scratched lines, as their name implies, being actually out into the surface of the roll and extending substantially longitudinally thereof, so that while the surface of the roll is much rougher than that of a roll with a dull finish, such surface is much smoother than that of a roll having the finest degree of corrugation, which it has been found practicable to produce. At the same time, however, I secure all of the advantages of the corrugated roll without any of the disadvantages, by reason of the fact that 1 secure the necessary gripping action on the particles of grain, and abraslon, or attrition, thereof due to the substantially straight character and longitudinal extension of the scratched lines.

' A further advantage of a roll roduced according to my invention is the act that the surface of the roll can be made almost absolutely true or' even, approaching absolute accuracy more nearly even than apolished roll and to far greater extent than a corrugated roll, with the result that the flour produced in the use of these rolls is characterized by uniform granulation, a hi hly desirable result in the milling art.

11 practicing my invention, the surface of the roll is first smoothed off by an emery wheel in the usual manner. Thereafter, I apply to the surface of the roll the side of an annular grindin wheel, the point of application bein su stantially 'at the termination of the orizontal diameter of the roll. The roll is then revolved, and .the grinding wheel in contact with the surface of the roll is also simultaneously revolved and moved endwise of the roll, with the result that with repeated travels of the grinding wheel from one end to the other of the roll, the entire surface thereof is subjected to the abrasive or inding action of the wheel. The size 0 the indin wheel and the difierential between its es of rotation and the speed of rotation o the roll are such that the grinding of the surface of the roll will be in substantially straight lines having, however, a diagonal or spiral extension on the cylinder. The surface of the roll will, by this means, he scratched in a uniform manner, and the coarseness of the abrasions produced on the surface of the roll will correspond to the coarseness of the grain of the material of the grindin wheel.

\ Such method of scratching the surface of I the roll possesses the advantages that it ma be performed with relative rapidity, an the surface of the roll will be uniform throu hout, as the latter is not subjected to a hen ing pressure, as is the case where it is attempted to corrugate. Furthermore, not only are the scratched lines of uniform depth, but as therelative positions of the roll and grinding wheel are fixed during the operation, :and as the relative rates 0 movement of the grinding wheel and roll, and the speed at which the grinding wheel is advanced longitudinally of theroll, are unchanged during the operation, it follows that the lines formed b the abrading points of the grinding whee are produced with exact uniformity throughout the whole operation.

In order that the invention may be fully understood, I have illustrated in the accompanying drawings an arrangement of apparatus by means of which the surface ofa grinding roll may be scratched in a manner herein described. In said draw- 1n igure 1 is a cross-sectional view through a grinding machine provided with the means w ich I em loy for practicing my improved method of nishing the surface of a roll;

Figure 2 is a view inbroken elevation ofv a grinding roll showing one end portion thereof provided with scratched lines in the manner effected by practicing the. method which I employ; and

Figure 3 is a view on an enlarged scale of the scratched surface shown in Figure 2.

It may be stated that Figures 2 and 3 were prepared from enlarged photographs of the surface ofa roll finished according to my invention, but the draftsman has found it practically impossible to exactly reproduce the efiect. It is believed, however, that Figures 2 and 3 sufficiently bring out the salient feature of the invention,

namely, that the scratched lines are substantially straight and have a diagonal extension relative to the axis of i the roll, although, owing to the curvature of the roll, they present the appearance of 'a spiral formation.

Referring now to the drawing, the numeral 1 indicates the upper portion of a grinding machine, having heads 2, on which a grinding roll 3 may be rotatably su ported. Mounted on the bed of this grin ing machine is a carriage 4, which supports a motor 5, the'shaft of which drives, through a belt 6, an annular grindin wheel 7. Means for producing longitudinal movement of the carriage 4 relative to the roll 3 and the means for rotating the roll are not shown, as they are of the usual, or any preferred, construction.

In the apparatus illustrated in my pending application referred to above, the grinding disk I use was relatively small and the lines, while having a general longitudinal extension, were nevertheless of curvilinear form and, therefore, intersected each other so that there was a billowy or wave-like efl'ect produced indicating that the lines of scratching were not continuous. To overcome this objection or, rather, to increase the beneficial action afforded by the scratched roll of my prior ap lication, whereby lines of scratching may e made substantially straight and continuous in their extent, that is, without intersectin other lines in 'a circumferential direction, employ the arrangement shown in the drawing in which a grindin wheel or annulus is substituted for the di of the application and the diameter of this wheel is considerably greater than that of, the disk which I previously employed. This grinding wheel, furthermore, is provided with a beveled side indicated at 8, and said beveled side is applied to the surface of the roll at the bottom side of the grinding wheel, which grinding wheel, as viewed from the ri ht in lUS nausea ing wheel 8 as comped with the grinding disk of my prior application, its vertical position and its manner of ap lication to the surface of the rinding r01, combined with the desired difi'erential of speed between the rinding wheel and roll, are the principal actors enabling me to produce lines of scratching on the surface of the roll, which are substantially straight and continuous.

As will be understood by those skilled inthe art, variations in the form and extension of the scratched lines can be readily efiected in various ways, as by changing the selected difierential between the' speed of the roll and grinding wheel, by changing the inclination of the grinding wheel, by changing the selected speed of movement of the grinding wheel longitudinally of the roll, and the like. ll conceive all such variations to come within the scope of the broad idea of the invention as claimed in my aforesaid pending application. a

The present application is directed to the specific embodiment of my invention in which the lines of etching or scratching are substantially straight and continuous, or free from intersection with other lines.

The grinding wheel 7 is preferably made of carborundum, and where a maximum coarseness in the scratching is desired, the carborundum will be of correspondingly coarse grain. If a less degree of coarseness of finish is desired, the grain of the carborundum wheel employed would be correspondingly less coarse.

Grinding rolls constructed according to my invention have, in actual demonstration, shown increased capacity, cooler grinding, the production of a whiter, more uniform and stronger flour, and one, having a slightly less ash content as compared with the action of smooth rolls. As compared with corrugated rolls, they require less power, a lower maintenance cost, have a longer life; and produce decided improvements in the character of the flour as respects such qualities as whiteness, uniformity, granulation, strength, bloom, lowness of ash content, and the like.

I claim:

1. A roll for milling wheat having its entire surface scratched along substantially straight distinct lines of relatively short len h having a general extension longitudinal of the roll. 7

2. A roll for milling wheat having its entire surface scratched along substantiall straight distinct lines of irregular lengt having a general extension longitudinal of the roll,

3. A roll for milling wheat having its entire surface scratched along substantially straight lines of relatively short length and irregular arrangement and having a general extension longitudinal of the roll.

4. A roll for milling Wheat having its entire surface ground-scratched along substantially straight lines of relatively short length and having a general extension longitudinal of the roll.

5. A roll for milling wheat having its entire surface ground-scratched along substantially straight lines of relatively short length and havmg a general extension longitudinal of the roll but diagonally positioned thereon 6. A roll for milling wheat having its entire surface ground-scratched along substantially straight lines having a general extension longitudinal of the roll, said lines of scratches being multitorm both longitudinally and circumferentially of the roll.

7. A roll for milling wheat having its entire surface scratched along substantially straight lines of relatively short length and irregular arrangement presenting a spiral formation on the roll.

In testimony whereof, I have hereunto set my hand.

LUDG SCHMIDT. 

